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Carcinoma of the Exocrine Pancreas in Medaka
Author(s) -
Hawkins William E.,
Fournie John W.,
Battalora Michael J.,
Walker William W.
Publication year - 1991
Publication title -
journal of aquatic animal health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 52
eISSN - 1548-8667
pISSN - 0899-7659
DOI - 10.1577/1548-8667(1991)003<0213:cotepi>2.3.co;2
Subject(s) - basophilic , pancreas , oryzias , biology , pathology , carcinogen , abdominal cavity , carcinoma , lesion , anatomy , endocrinology , medicine , genetics , fishery , fish <actinopterygii>
Abstract Eight cases of carcinoma of the exocrine pancreas were diagnosed in medaka Oryzias latipes from a pool of about 10,000 specimens used in carcinogenesis tests of a variety of compounds. Three cases occurred in specimens from control groups and one case in a specimen treated with benzo[ e ]pyrene, a noncarcinogenic isomer of benzo[ a ]pyrene. Four cases occurred in specimens treated with compounds that were carcinogenic to medaka. These included two cases in specimens treated with 7,12‐dimethylbenz[ a ]anthracene, one treated with benzo[ a ]pyrene, and one treated with methylazoxymethanol acetate. Pancreatic carcinoma was likely to have been the cause of death in each of the five cases. The neoplasms appeared to originate in the abdominal mesentery. Tumor cells infiltrated the peritoneal cavity and retroperitoneal spaces, invading the gonads, intestine, and kidney. In several cases, the tumors metastasized through the blood, as evidenced by tumor emboli in the heart and tumor cells trapped along trabeculae of the atrial myocardium. Tumor cells, which we believe were of acinar cell origin, were basophilic and poorly differentiated, had a high nucleus‐to‐cytoplasm ratio, exhibited numerous mitoses, and tended to form cords and lobules. Based on the scattered occurrence of the tumors and the fact that a concentration‐response relationship was not evident even in those cases developing after exposure to strong carcinogens, we consider the lesion to be spontaneous.